Abstract: The inventive waveguide structure comprises a first waveguide region having a constant first width adapted to guide electromagnetic waves mode sustainably along its longitudinal axis; a second waveguide region adapted to guide electromagnetic waves mode sustainably along its longitudinal axis, wherein the longitudinal axis of the first waveguide region and the longitudinal axis of the second waveguide region form a common longitudinal axis of the waveguide structure, wherein a first end face of the first waveguide region and a first end face of the second waveguide region are aligned with each other, the width of the first end face of the second waveguide region corresponding to the first width, and the width of the second waveguide region along its longitudinal axis widens from the first end face to a second end face to a second width greater than the first width.

Abstract: Laser diode comprises an active layer; a waveguiding region at least partially surrounding the active layer; a rear facet; a front facet designed for decoupling laser radiation, wherein the active layer extends at least partially along a first axis (X) between the rear facet and the front facet; and a grid operatively connected to the waveguiding region, wherein the grid comprises a plurality of webs and trenches designed such that an average increase of a coupling parameter P for the plurality of trenches along the grid is non-zero, wherein the coupling parameter P of a trench is defined by the formula, wherein dres is a distance of the trench to the active layer, w is a width of the trench and ?n is the refractive index difference between a refractive index of the trench and a refractive index of a material surrounding the trench.